Means for securing conductors to outlet boxes



P 1953 s, D. J. DUNLAP 2,652,269

MEANS FOR SECURING CONDUCTORS TO OUTLET BOXES Filed Jude 7, 1950 INVENTOR. .Slmuu 11a. nun/.49

Patented Sept. 15, 1953 UNITED STATES PATENT OFFICE MEANS FOR SECURING CONDUCTORS TO OUTLET BOXES Samuel D. J Dunlap, Detroit, Mich. Application June 7, 1950, Serial No. 166,670 1 Claim. (01. 28720) This invention relates to conduit clamps, and.

more particularly to a clamp for securing electrical conduits toapertured electric outlet boxes or similar structures.

It is the object of the present invention to provide an improved clamping devicewhich may be manufactured in quantities preferably as stampings, or which may be constructed of a plastic substance.

It is the further object of this invention to provide a clamping device of simplified construction with a minimum number of parts which may be readily assembled upon the electrical conduit adjacent an aperture in the outlet box forthe purpose of securing the cable in rigidrelation to the wall of said box.

These and other objects will be seen from the following specification and claim in conjunction with appended drawing in which:

Figure l is a side elevation of the assembled clamp and electrical conduit, illustrating the same in secured position to the apertured side wall of an electric terminal box, switch box or outlet box which is fragmentarily shown andsectioned.

Figure 2 is a section on line 2-2 of Figure 1.

Figure 3 is a section on line 3--3 of Figure 2.

Figure 4 is a front elevational viewof the'clamp shown in Figure 1 but with the'screwuntightened,

and with the cable or conduit-shown in section.

Figure 5 is a section on line 5- 5 of Figure 2.

Figure 6 is a section on line 6-6 of Figure 2.

Figure 7 is a fragmentary elevationalview of a variation in the formation of the clampfianges.

Figure 8 is a section on line 8-8 of Figure 7.

Figure 9 is similar to Figure '7; but aslig-htvariation.

Figure 10 isa section on line Ill-10. of Figure 9.

Figure 11 is similar to Figure 7, but. showinga variation thereof.

Figure 12 is a section on line |2--l2 of. Figure 11.

Figure 13 is similar to Figure '7 but showinganother variation thereof.

Figure 14 is a section on line I l-14 of. Figure 13; and

Figure 15 is a section on line 5-4 5 of Figure 4.

It will be understood that the above drawing illustrates merely a preferred embodiment of' the invention, and that other embodiments are contemplated within the scopeof the claim hereafter set out. 1

Referring to the drawing, the interconnecting cooperating clamp members comprise two com- 2 plementary rigid plate members I 0 and ltformed of metal or plastic, and: which are preferably sheet metalstampings. a

Each. plate member includes an. intermediate outwardly curved: concave conduit. holding portions I3 and IBarespcctively terminating at one in. the right angularoutwardly extending in.- tegral flanges l4 and Hlawhich are arrangedin alignment and extend in opposite directions when said platemembers are assembled upon the cable or conduit C;

Plate member H1 at the side of its outwardly curved intermediate portion I3, is provided with a projecting ear l5 of. reduced width andset. ofii upon one side from said'intermediateportion by the shoulder [5a, such as is shown in Fig. 1. A threaded opening I8 is: provided through. theyear l5 adapted for reception of' the screw or bolt I! as shown in Fig. 2. v i

The opposite portion of; clamp element In includes a substantially flat straightrigid wall portion t8, which issalso. inwardly set off. upon one side fromthe intermediate: curved. portion I3 by the shoulder I5a, suchas shown in Fig. 1.

Wall portion lafl' terminates in theinwardly offset aligned projecting. tongue l5, which is curved outwardly and'which iso'f. reduced width so. as to leave oppositely disposed flatshoulders 20 at. the juncture of wall l8. and said? tongue as indicated in dotted lines in Fig.1..

The. other clamp element i. e. plate member I2 also includes a central concave outwardly curved intermediate portion I311, and there is provided upon one side of said intermediate. portion an ear 2| of the same shape as ear [5. Outwardly inclined $1012.22 is formed Within the ear 2| in general registry with the threaded opening Hi, being adapted to. loosely receive the screw or bolt l1.

As will be seenhereinafter the elongatedislot 2 2 shown in Fig. 6 willpermit additional adjustment of the platev membersl Ill; and: I2 with respect to each other facilitating insertion of the conduit C therebetween; and also facilitate the insertion of the flanges I Land Ida: throughthe aperture-D in the side wa A of. the electrical outlet box B as shown in Fig. 1..

The ear isalso. set on. upon oneside from the intermediate'arcuate portion [3:1 by the shoulder I50. shown in Fig. 1. The oppositeportion of the plate'member I2 corresponding to wall portion. t8 of plate member Ht also includes a straight-wall portion 23 WhlCh is similarly set off upononeside defining the upper shoulder l5a: as viewed: in Fig.1 1". r

Straight wall portion 23 terminates in the angularly inturned portion 25 as shown in Fig. 2, there being a rectangular enlarged slot 26 therein adapted to loosely and cooperatively receive tongue I9 of plate member iii. The enlarged slot 26 thus permits of lateral adjusted of the plate members I and I2 with respect to each other, but with the upper ends thereof loosely joined as shown.

From the foregoing it will be apparent that clamp members it! and I2 may be readily and easily assembled in conjunction with the electric conduit C so as to securely anchor the same to said clamp members and with the latter in rigid immovable relation to wall A of the terminal box or the line B having the usual aperture D to receive therethrough conduit C and the interconnected oppositely extending flanges I l and Ida of plate members it) and I2.

It will be understood that the terminal box B houses and protects any desired electrical outlet or source of current (not shown) to which the ends of the wires of said conduit are communicably connected as by the usual binding posts, and the opposite exterior portion of the conduit may lead to any desired switch controlled electrical fixture where thecurrent to be utilized may be energized at the will of the user.

The front upright edges of plate members IE3 and I2 are turned outwardly to form the shoulders 2i and 28 Fig. 4, which not only reinforce said members, but also provide a throated opening between said members to facilitate insertion of the conduit therebetween.

The central concave portion Ida of plate member I2 has an outwardly projecting portion 29 formed therein for registry with the outer surface of conduit C. There is formed within the opposing intermediate member I3 of plate member I!) an angularly inturned grip or projection 3i: which is pointed at 3|, and which is adapted for slight retaining penetration into the outer wall of conduit C, for cooperation with the projection 29. Furthermore, projection 30 is ofi-set laterally with respect to projection 29 to more effectively in cooperation therewith secure said conduit between the arcuate portions of plate members I0 and I2.

The flanges Hi and inner surfaces the fulcrums 32 which are adapted for registry with the inner surface of the wall A of the box B adjacent its aperture D, such as is shown in Figs. 1, 4 and 15. The fulcrums 32 provide a means of slightly spacing portions of the flange I l and Ma from the interior surface of the outlet box wall A.

This means that in the preferred embodiment of the present invention said flanges will be arranged at right angles to the bodies of the plate members iii and I2 and the fulcrums 32 will be in cooperative engagement with the inner surface of wall A.

In assembling the parts upon outlet box B through the aperture 1), the tongue 29 of clamping plate It] is loosely inserted into the corresponding slot 26 of plate member i2. With members l9 and I2 and their corresponding concave portions I3 and I30. disposed in loose engagement with opposite sides of the conduit C on the exterior of said box, the oppositely extending flanges I4 and Ida are inserted through the box aperture D.

The slot 22 of plate member I2 is brought into opposed registry with the threaded opening it I ia have formed upon their inwardly extending legs or I 33 at the outer of plate member Ill and the screw or bolt IT is loosely inserted through slot 22 and into the threaded opening I6 for holding engagement with plate l0. Continued rotation of the screw or bolt M will draw the opposed ears towards each other until the respective intermediate curved portions I3 and [3a fulcrum outwardly upon the conduit in tight clamping engagement therewith, which is effectively obtained as soon as the tongue It bears against the wall of the slot 26 in tight immovable relation.

The corresponding shoulders Hia at the inner sides of the engaged clamping members Iii and I2 are of sufficient length to afford clearance with a minimum of tolerance for the box wall A so as to immovably fit in fixed relation between flanges Id and Ma. and the adjacent edges of the opposed wall portions I8 and 23 and the ears l5 and 2I as illustrated in Fig. l of the drawing.

When the screw i1 is effectively tightened, the projections 22 and 36 formed upon the inner surfaces of arcuate members I3 and Its tightly grip the outer opposing walls of the conduit C to more eifectively grip said conduit than would be done with said projections omitted.

Thus any strains imparted upon the conduit C are transmitted through the plate members IE] and I2 and the flanges I4 and Ma thereof and the wall A of the box B, thereby relieving the inner portion of the conduit from such strains which might otherwise tend to loosen or disrupt its connection with the enclosed electrical binding posts.

By employing the legs or fulcrums 32 in the flanges I4 and I la, it is apparent that said flanges will be positioned substantially parallel to the inner surface of the box wall A. Thus when the screw ii is tightened, the clamping members IE2 and I2 are locked against the box walls with the intermediate portions I3 and Ida tightly engaging the conduit.

Figs. '7 and 8 illustrate a variation in the formation of the fulcrums in the flanges M and Ida, in that the same are formed as inturned portions ends of said flanges.

In Figs. 9 and 10 another variation is shown wherein a central portion at the outer ends of the said flanges is cut and turned inwardly defining the fulcrums 34.

In Figs. 11 and 12 the fulcrums are formed by the inwardly depressed portions 35; whereas, in Figs. 13 and 1 the fulcrums are provided by a pair of spaced inwardly depressed circular portions 36.

The variations in the formation of the fulcrums for the flanges I4 and Ma as shown in Figs. 7 through 14, are merely illustrative of various methods by which the same may be constructed all for the same purpose as the fulcrums 32 which are shown in Figs. 3 and 15, and which are adapted for cooperative compressive engagement with the inner wall A of the box B adjacent its aperture D through which conduit C extends.

By providing the inclined slot 22 in the ear 25 of plate l2 it is apparent that there may be some relative adjustment of plate members It and I2 with respect to each other without further loosening of the screw i? or its removal, such as illustrated by the dotted lines in Fig. 4. Furthermore, a greater degree of relative adjustment is provided between the members it and I2 by virtue of the enlarged slot 26 at the upper end of plate member I2.

Having described my invention, reference I5 and 2t should now be had to the claim which follows for determining the scope thereof.

I claim:

Means for clamping an electrical conduit to an outlet box having a conduit receiving aperture therein, comprising a pair of separable complementary plate members each having an intermediate conduit engaging portion terminating at one end inan outwardly extending flange arranged normally thereof for positioning adjacent the interior of the box wall adjacent said aperture, fulcrum means projecting inwardly from said flanges for engaging the interior of said box wall, an ear extending from one side of each of said intermediate portions and a wall extending from the opposite sides thereof, corresponding aligned edges of said ear and wall being spaced inwardly from said flange to engage against the exterior of said box wall adjacent said aperture, said walls of the respective membershaving tongue and slot engaging means, there being a threaded opening and an enlarged inclined slot respectively formed in the adjacent pair of ears, a threaded fastening member loosely projected through said slot and through said threaded opening to draw said members together to clamp the conduit therebetween with their fulcrum means engaging the inner box wall surface, said fastening member being adapted for transverse movement within said slot, and opposed longitudinally olfset conduit gripping elements projecting inwardly from the inner surfaces of said conduit engaging portions, the opposed outer edges of said plate members being outturned to form a throated portion to facilitate the insertion of said conduit therebetween.

SAMUEL D. J. DUNLAP.

References Cited in the file of this patent UNITED STATES PATENTS 

